Exclude corona-schnelltest-zentren.dm.de from link test

[MikeMcC399]

• This PR addresses the link test failure in job 4401083360

"AssertionError: Link: https://corona-schnelltest-zentren.dm.de/o/dm/login: expected false to equal true"

arising from using the link in blog articles.

• It adds the hostname corona-schnelltest-zentren.dm.de to the list noCheckHosts in cypress/e2e/hybrid/check_links.cy.js, since https://corona-schnelltest-zentren.dm.de/o/dm/login responds with a 404 (Not Found) error.

curl -I https://corona-schnelltest-zentren.dm.de/o/dm/login
HTTP/2 404
content-type: text/plain; charset=utf-8
x-content-type-options: nosniff
content-length: 19
date: Mon, 13 Mar 2023 09:12:05 GMT

• Due to legal changes in TestV also mentioned in Legal changes in TestV affect app and website #3415 many test centers shut down with effect from March 1, 2023.

[brianebeling]

Thanks for the PR!